<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        .cover-img {
            width: 600px;
            height: 300px;
            margin: 100px auto;
            border: 3px solid #FFA500;
            position: relative;
            overflow: hidden;
        }

        .cover-img .sed-img {
            width: 100%;
            height: 100%;
        }

        .cover-img .mask-img {
            width: 100%;
            height: 300px;
            position: absolute;
            background-color: rgba(0, 0, 0, 0.5);
            text-align: center;
            line-height: 300px;
            top: 0;
            left: 0;
            box-sizing: border-box;

        }


        .cover-img .mask-img {
            display: none;
        }

        .cover-img:hover .mask-img {
            display: block;

        }
    </style>
</head>

<body>
    <div class="cover-img">
        <img class="sed-img" src="./images/sed.jpg" alt="">
        <div class="mask-img">
            <img class="observer-img" src="./images/arr.png" alt="">
        </div>
    </div>
</body>

</html>